Automatic safety brake system



United States Patent Ofilice 3,015,522 Patented Jan. 2, 1962 3,015,522AUTOMATIC SAFETY BRAKE SYSTEM Richard B. Spikes, 2421 4th Ave., LosAngeles, Calif. Filed Oct. 26, 1959, Ser. No. 848,655 8 Claims. (Cl.303-9) The present invention relates to improvements in a brakingsystem, and more particularly to braking systems for wheeled vehicleswhich provide a reserve braking action in case of damage to the normalbraking means.

Many vehicles, such as automobiles, utilize hydraulically actuated brakeshoes which frictionally contact brake drums or disks carried by thevehicle wheels in order to stop or slow down the vehicle. When, for anyreason, hydraulic pressure is lost, there is a corresponding loss ofbraking action.

Dual braking systems have been proposed wherein travel of the foot pedalpast a designated point will mechanically pull on cables, which will inturn force the brake shoes into contact. The loss in braking efliciencybetween the hydraulic and mechanical systems i dangerous, and, by givinga false sense of confidence to the driver, is likely to result inserious accidents.

A further objection to the described system is the necessity of designcompromises to permit the free run of the actuating cables and toprovide the necessary space for the mechanical system.

The present invention contemplates a dual, or doubleacting, brakingsystem which is entirely hydraulically actuated. This provides equalbraking efl'iciency for both the primary and secondary or reserveactuating systems, and the flexibility of location possible withhydraulic lines solves the design problems having to do with lack of.space.

It is, therefore, a principal object of the present invention to providea hydraulic brake system having a primary brake actuating means and asecond, reserve hydraulically operated brake actuating means which willautomatically take eflect in case of breaks or leaks in the primary por'tion of the system.

Another object of the present invention is to provide a dual brakingsystem having primary and auxiliary hydraulic means for actuating thesame brake shoes with a similar degree of efliciency so as to provide asmooth transition from the primary to the auxiliary braking means.

A further object of the invention is to provide a dual braking system ofthe character described in which the transition from the primary to theauxiliary actuating means is signalled to the foot of the operator toinform him that some flaw exists in the primary system.

A still further object of the present invention is the provision, in adual braking system of the character set forth, of a valving means whichpermits the use of a single master cylinder for both systems.

And finally, it is proposed to provide a valving means of the characterdescribed which is actuated by travel of the foot pedal or other brakeactuating control past a predetermined point, and which will visuallysignal to the operator that the valving means has operated to cut oflthe primary system and connect the reserve system.

Further objects and advantages of my invention will appear as thespecification continues, and the new and useful features of the samewill be fully defined in the claims hereto attached.

FIGURE 1 shows a plan schematic view of a dual braking systemconstructed in accordance with the present invention and applied to afour Wheeled vehicle;

FIGURE 2, an enlarged vertical sectional view of the master cylinder andassociated structure taken substantially on the plane of line 22 ofFIGURE 1;

FIGURE 3, an enlarged vertical sectional view of the brake assembly andactuating cylinders taken substantially on the plane of line 3-3 ofFIGURE 1;

FIGURE 4, an enlarged vertical section view of a valving means takensubstantially on the plane of line 4--4 of FIGURE 1; and

FIGURE 5, a plan sectional view of a valving means taken substantiallyon the plane of line 5-5 of FIG- URE 4.

While I have shown only the preferred form of my invention, I wish tohave it understood that various changes or modifications may be madewithin the scope of the claims hereto attached, without departing fromthe spirit of the invention.

Referring to the drawing in detail, it will be seen that the brakesystem of the present invention consists basically of primary andauxiliary brake actuating means 11 and 12, which are operative uponenergization to apply friction brakes 16, energizing means 13 for theactuating means which is controlled by a manually operable member 14,and sensing means 17 operable to disconnect the primary brake actuatingmeans 11 from the energizing means 13, and simultaneously connect theauxiliary brake actuating means 12 thereto, upon movement of said member14 beyond a predetermined range of movement.

FIGURE 1 illustrates the arrangement of parts used in connection with afour wheel vehicle. As here shown, the brakes 16 are of the internallyexpanding type in which a pair of brake shoes 18 and 19 are pivoted onpins 21 for outward movement into contact with the inner periphery of abrake drum 22 mounted upon the vehicle wheel (not shown).

The brake shoes 18 and 19 are urged outwardly by a cam 23 positionedbetween the confronting free ends of the brake shoes. Rotation of thecam in either direction, from the neutral position illustrated in FIGURE3, will urge the brake shoes apart and into frictional contact with thebrake drum 22.

The primary brake actuating means 11 is designed to rotate the cam 23 inone direction, when energized, while the auxiliary actuating means l2urges the cam in the opposite direction when the sensing means 17connects the auxiliary actuating means 12 to the energizing means 13.

As may be best seen from FIGURE 3 of the drawings, the primary actuatingmeans 11 includes a hydraulic cylinder 24 which is supported by thevehicle axle housing (not shown) in position for its piston '26 todisplace a lever 27 connected to cam 23 for applying the brakes wheneverfluid under pressure is supplied to cylinder 24.

Mounted in aligned opposition to cylinder 24 i a similar cylinder 28forming part of the auxiliary actuating means 12. The piston 29 ofcylinder 28 bears against the side of lever 27 opposite to cylinder, 24and serves to rotate the cam 23 in the opposite direction whenever fluidunder pressure is supplied to cylinder 28.

It will be noted that the cylinders 24 and 28 are of the same size, andthe effective lever arm they employ in rotating cam 23 is the same. Thisresults in identical braking eflect whichever cylinder is operating.

Fluid under pressure is supplied by the energizing means 13, which hereconsists of a master brake cylinder 31 operated by the usual brake pedalarm 32 providing the manually operable member 14, see FIGURE 2.Preferably, the master brake cylinder 31 is somewhat longer than theconventional unit in order to provide for a somewhat longer travel forthe piston 33 in it chamber 34. Otherwise, the construction isconventional and includes a. fluid reservoir 36 and piston return,spring 37.

A supply line 38 communicates the master cylinder chamber 34-with valvemeans 39 which form a part of the sensing means 17. Preferably, thereare two valve means mounted on the front and rear of the vehicle andoperative for selectively communicating the supply line 3 38 with eitherthe primary brake actuating cylinders 24 or the auxiliary cylinders 28.

As here shown, the valve means 39 each consists of a two-way valvehaving a pair of conduits 41 leading to the primary cylinders 24 of theadjacent wheels, and a pair of conduits 42 leading to the auxiliarycylinders 28.

The valves 39 are here or" the rotary type, shown in FIGURES 4 and ofthe drawings, and consist of a rotor 43 mounted for limited rotation ina housing unit 44. The supply line 38 opens to the hollow center of therotor 43 from which extends radial passages 44a and 44b.

The passages 44a are proportioned to register with ports leading toconduits 41, in one terminal position of the valve and passages 44b areformed to register with the conduits 42 in the other terminal positionof the valve. The passages 44a are normally aligned with conduits 41,while passages 44b communicate with relief ports 46 through cut-outportions of the rotor. These connections are reversed when rotor 43 ismoved to its other terminal position. Passages 44a and 44b are blockedoff when not in registry with their respective conduits and ports 46 maybe connected to reservoir 36 through suitable conduits (not shown).

As will be noted from FIGURES 1, 4 and 5 of the drawing, the valves 33are double two-way valves, that is, there are two ports leading toprimary supply lines 41 and two ports leading to auxiliary supply lines42. This structure insures that opening of either set of ports will besimultaneous and proportional and thus application of the brakes on theopposite sides of the vehicle will be completely balanced at all times.

The sensing means 17 includes means for operating the valve between itsterminal positions to shut off fluid from the primary cylinders 24,should they or their supply conduits develop a leak, and to supply thefluid to the auxiliary or reserve cylinders 28. This means here consistsof a solenoid 47 adapted to drive a rack gear 48 which is enmeshed witha pinion gear 49 secured to the valve rotor 43. Upon energization of thesolenoid, the

rack will move and cause the valve rotor to move to the terminalposition actuating the auxiliary cylinders.

The solenoid is connected by leads 51 and 52 to a source of electricalenergy, such as the vehicle battery (not shown). Interposed in one ofthe leads is a switch 53 which is mounted in the path of travel of thebrake pedal 32 or piston 33 so as to be closed when the piston passes apredetermined position in the cylinder chamber 34.

Whenever a predetermined quantity of fluid is lost from the system, thepiston 33 will pass the predetermined point and the switch 53 willcomplete the circuit to the solenoid 47. The loss of fluid may be causedby leakage from any part of the system, but usually occurs due to wearor injury of the wheel cylinders or the flexible conduits leadingthereto.

Completing of the circuit to the solenoid 47 will cause the valves 39 toswing to their other terminal position, disconnecting the primarycylinders 24 and their conduits 41 from the pressurized system, andconnecting the auxiliary cylinders 28 to the master brake cylinder.

The elfect of this is to cause the cam 23 to swing in the oppositedirection and apply the brakes. A light 54, mounted on the dashboard andconnected into the solenoid circuit, visually indicates when the reservebrake actuating means comes into play. The operator can also feel thechangeover during the tiny period in which the cam 23 swings to itsauxiliary braking position.

While the dual braking system has been described for use in connectionwith four-wheel vehicles, it should be noted that the system is equallyeffective with vehicles having more or less wheels. When used withmultiple wheel units, one valve 39 may conveniently serve each pair ofwheels, although other arrangements may be made.

Thus, it will be seen that I have provided a novel double-acting brakingsystem having primary and auxiliary brake actuating cylinders, whichwill automatically switch from the primary to the auxiliary cylindersupon loss of a certain amount of fluid from the system. This gives thedriver complete control of braking under all conditions and even if theprimary actuators become inoperative due to breaks or leakage. Suchcontrol is an important factor for safety, and may prove the diiferencebetween life or death.

I claim:

1. In a dual braking system for automotive vehicles, a primary hydraulicbrake actuating cylinder at each wheel, a master cylinder adapted forproducing fluid under pressure upon movement of a piston therein, anauxiliary hydraulic brake actuating cylinder at each wheel, valve meansconnecting said primary brake actuating cylinders and said auxiliarybrake actuating cylinders to said master cylinder in first and secondterminal positions respectively of said valve means, and sensing meansoperatively connected to said piston and adapted for actuating saidvalve means from said first position to said second position uponmovement of said piston past a predetermined point in said cylinder.

2. In a dual braking system for automotive vehicles, a primary hydraulicbrake actuating cylinder at each wheel, a master cylinder adapted forproducing fluid under pressure upon movement of a piston therein, anauxiliary hydraulic brake actuating cylinder at each wheel, valve meansconnecting said primary brake actuating cylinders and said auxiliarybrake actuating cylinders to said master cylinder in first and secondterminalpositions respectively of said valve means, said valve meansincluding electrically powered actuating means for moving said valvemeans between said terminal positions, and sensing means operativelyconnected to said piston and adapted for actuating said valve means fromsaid first position to said second postion upon movement of said pistonpast a predetermined point in said cylinder, said sensing meansincluding an electrical circuit having a switch operable upon saidmovement of the piston past the predetermined point.

3. In a dual braking system for automative vehicles, a primary hydraulicbrake actuating cylinder at each wheel, a master cylinder adapted forproducing fluid under pressure upon movement of a piston therein, anauxiliary hydraulic brake actuating cylinder at each wheel, a fluidsupply conduit from said master cylinder, a pair of valves positioned incommunication with said conduit at the front and rear of the vehicle,said valves being of the two-way type and adapted for selectivelyconnecting said conduit with the primary and auxiliary actuatingcylinders of the front and rear sets of wheels respectively, and valveoperating means having an operative connection to said piston and formedfor controlling said valves to communicate said conduit with saidprimary actuating cylinders while said piston is positioned in apredetermined portion of said master cylinder and for reversing saidvalves when said piston is out of said predetermined portion of saidmaster cylinder.

4. In a dual braking system for the wheel of an automotive vehiclehaving friction brakes for slowing rotation of the wheel, a pair ofhydraulic brake actuating cylinders, a master brake cylinder having afluid supply, a two-Way valve connected to said brake actuating andmaster cylinders and formed for selectively supplying fluid underpressure from the master cylinder to one of said brake actuatingcylinders in one terminal position and to the other actuating cylinderin its other terminal position, and electrically operated means forpositioning said valves in one terminal position during normal operatingcondition of said master cylinder and for positioning said valve in theother terminal position upon depletion of said fluid supply at saidmaster cylinder.

5. A dual braking system of the character described in claim 4 andwherein said two-way valve is of the rotary type, and said electricallyoperated means is adapted to rotate said valve.

6. A dual braking system of the character described in claim 5 andwherein said electrically operated means includes a rack and piniondrive for said valve, a solenoid connected to said rack, and anelectrical switch operable by movement of the piston in said mastercylinder beyond a predetermined position.

7. In an automotive vehicle having brake drums carried by each wheel forfrictional engagement by outwardly movable brake shoes pivoted on thevehicle, a dual braking system, comprising a cam rotatably mountablebetween the brake shoes at each wheel and formed to spread such brakeshoes when rotated in either direction, an arm extending from said camfor rotating the latter when the arm is displaced from a centeredposition, primary and auxiliary hydraulic cylinders mounted inconfronting relation with said arm interposed therebetween fordisplacement in a first direction when fluid un- 'er pressure issupplied to said auxiliary cylinder, a master cylinder adapted forproducing fluid under pressure upon movement of a piston therein, valvemeans connecting said primary brake cylinders and said auxiliary brakeactuating cylinders to said master cylinder in first and second terminalpositions, respectively of said valve means, said valve means includingelectrically powered actuating means for moving said valve means betweensaid terminal positions, and sensing means operatively connected to saidpiston and adapted for actuating said valve means from said firstposition to said second position upon movement of said piston past apredetermined point in said master cylinder, said sensing meansincluding an electrical circuit having a switch operable upon saidmovement of the piston past the predetermined point.

8. A dual braking system as defined in claim 7, and wherein said valvemeans includes a valve having a rotor movable between terminal positionand formed with passages adapted for communicating said master cylinderwith said primary cylinder during the first position of the stroke ofsaid piston and with said auxiliary cylinder upon a continuing portionof said stroke whereby the changeover from said primary to saidauxiliary cylinder will release the brakes for a tiny instant and thussignal the driver that the system has switched to auxiliary braking.

References Cited in the file of this patent UNITED STATES PATENTS1,650,286 Livingston Nov. 22, 1927 2,464,469 Tremolada Mar. 15, 19492,649,169 Holman Aug. 18, 1953 2,871,827 Euga Feb. 3, 1959

